“If the owner does not opt for the affordable housing scheme then the NDZ norms will apply which is currently 0.2 FSI. The scheme is very attractive and we are hopeful that many owners will come forward,” said BMC commissioner Ajoy Mehta.

For big land owners including private trusts and companies such as Byramjee Jeejeebhoy Group, Rahejas and Godrej & Boyce, the offer is the first such concession by planners, who have historically sought to regulate population growth by restricting construction inside the city.

This time though, land has been demarcated in the suburbs to add 10 lakh affordable homes to Mumbai’s housing stock. This includes about 130 hectares of salt pans, 1,100 hectares of tourism development areas and 2,100 hectares of privately-owned NDZs.

The only catch is: the DP does not delineate areas on NDZ lands which would be earmarked for affordable housing— the promise of housing within city limits for middle and lower income groups, though unexceptionable, is not backed by any reservation. BMC’s new development control rules broadly outline a proposal for division of land into three parts if an NDZ landlord comes forward; the owner would then have to surrender 66% of the land for affordable housing, public open spaces and other amenities, and in return, get to exploit the remaining 34% with a floor space index of 3.

Some activists say the plan bears an uncanny resemblance to the one-third land formula used to develop defunct mill plots in central Mumbai, a framework which was altered on the demands of developers and eventually created little or no open space and social infrastructure.

Pankaj Joshi, executive director, Urban Design Research Institute said, “The fear in civil society is that the new DCR may also be tweaked to give more land to the owners rather than for affordable housing. The city could lose out,” he said.

Asked why the BMC had not earmarked reservations for affordable housing on NDZs on the Development Plan maps as it has done for other land parcels around the city, Mehta said the rules laid down are sufficient to ensure the targets are met.

Activist and architect, P K Das, however, disagreed. “Government hopes landowners will be lured by an incentive FSI of 3 to develop their land for affordable housing. But the DP suggests only 25% of NDZ land to be developed for affordable housing. Assuming land-owners of all the 3,330 hectares take advantage, only 25% of that land—about 830 hectares—will be available for affordable housing. That translates into 85,000 affordable units,” he said.

Civic officials too conceded that government’s target of five lakh affordable units on NDZ land was unrealistic. In all, city has 13,706 hectares of NDZ land of which 75% has been set aside as ‘Natural Areas’ characterized by mangroves, mud flats, creeks, estuaries, where no construction is permitted. It is from the remaining 3,355 hectares that BMC seeks to separate 2,100 hectares for the mass housing project.